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Z Machine IV

StarDate:

February 6, 2014

White dwarf stars are handy to have around. Astronomers use them to help measure the age of the galaxy, to plot the effects of dark energy and dark matter, and to understand how matter behaves in extreme conditions.

For white dwarfs to be helpful, though, scientists need to know how heavy they are and how hot they are. With those traits, the scientists can determine how old the stars are and much more.

There are two ways to learn about white dwarfs. One is to study the stars themselves, which astronomers have been doing for many decades. The other is to study white dwarf conditions in the laboratory. And for the last few years, a team led by Texas astronomer Don Winget has been doing just that.

The team has been using the Z Machine at Sandia National Laboratories. The machine zaps a test-tube-sized sample of hydrogen, which is the main ingredient in the atmospheres of most white dwarfs, with X-rays. That heats the gas to thousands of degrees — just like on the surface of a real white dwarf. That allows the scientists to measure white dwarf conditions not across many light-years, but from just a few inches.

The measurements are serving as a benchmark — a way to calibrate observations of real white dwarfs, improving the measurements made by telescopes. And that will help refine our knowledge of dark energy and dark matter, the evolution of our home galaxy, and much more — knowledge made possible in part by astronomy in a test tube.

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